Foliar feeding

Hi, I haven't heard much on the subject (maybe I was looking in the wrong place) can anyone enlighten me on the subject of foliar feeding. I normally fertilize by watering in the medium and not on the leaves of the plant, am I missing something by ignoring the leaves? Thanks Hank.....

I have seen this subject debated other places, but I'm not sure there is a definitive answer. Many people feel that foliar feeding in orchids has limited value because orchid leaves have relatively few stomata, so the fertilizer doesn't enter the plant easily. Others swear by it. I have seen foliar feeding formulations, and my biggest question has been whether or not foliar feeding products could be used for root feeding. I haven't gotten a straight answer about that either.

I am one person who will definitely swear by foliar feeding, from the day I bought orchids I have fertilized only by foliar application. The Plants also get fertilizer at their roots because when I water my plants, I always wash the foliage, so any fertilizer residue left on the leaves dissolves and reaches the root zone.

Many people feel that foliar feeding in orchids has limited value because orchid leaves have relatively few stomata, so the fertilizer doesn't enter the plant easily.

Stomata are meant only for the exchange of gases, even plain distilled water cannot enter orchid leaves through the stomata, only in the form of water vapour can water traverse through the stomata. The mechanism by which fertilizer can enter leaves, is by special channels across the cell membrane.

Originally Posted by orchidlady

I have seen foliar feeding formulations, and my biggest question has been whether or not foliar feeding products could be used for root feeding. I haven't gotten a straight answer about that either.

Susan

Reading the ingredients is very important, usually good quality foliar fertilizers are the best fertilizers as they have very good solubility. Look for the the nitrogen source any fertilizer with more than 100 ppm of Nitrogen in the form of Urea is not good. Potassium in the form of KNO3 or KH2PO4 are good sources. And Phosphorus sources should be either Phosphoric acid, Ammonium phosphate or Postassium phosphate.

I like foliar feeding, especially for the mounted plants. I also have found foliar feeding gets better result(than root feeding) When I feed my plants with Epsom salt. (Based on my own experience, an extra doze of magnesium(Epsom salt) can be benefitial for the plants that grow under artificial light.)

Stomata are meant only for the exchange of gases, even plain distilled water cannot enter orchid leaves through the stomata, only in the form of water vapour can water traverse through the stomata. The mechanism by which fertilizer can enter leaves, is by special channels across the cell membrane.

One of the possible mechanisms is that some of the feeding formulation components become converted to gas form (ie ammonia and carbonic acid). Another mechanism suggested has been by transcuticular pores like you suggested. Perhaps it is a combination of both.

Reading the ingredients is very important, usually good quality foliar fertilizers are the best fertilizers as they have very good solubility. Look for the the nitrogen source any fertilizer with more than 100 ppm of Nitrogen in the form of Urea is not good. Potassium in the form of KNO3 or KH2PO4 are good sources. And Phosphorus sources should be either Phosphoric acid, Ammonium phosphate or Postassium phosphate.

One thing that generally has been agreed upon is that foliar feeding is not an efficient way of giving the major nutrients. Root feeding is better in that respect. The foliar feeding formulations I have looked at are composed of micronutrients. They are somewhat expensive, so I have been reluctant to try something that may or may not be effective. That being said, when I do regular fertilizing, some gets on the leaves as well as in the medium.

It would be nice to see controlled scientific evidence regarding foliar feeding, its mechanism, and efficiency. Most of the evidence I have heard has been anectodal such as mentioned here.

Of course you can use foliar type plant food for root feeding. I went to automated sprinklers several years ago to provide more consistency and they get the food in the water... Think about how they grow in nature.... do they only get water from rain or condensation? do they live in flood prone areas where the roots are the only part to get wet?

This is one reason its important to know where they originally come from.
But then, All mine get sprayed and misted... that's what rain does- right?

As for scientific studies... I think Orchids magazine ( AOS) had an article on that 2 years ago...

I am a believer in foliar feeding as well and have used epsom salts for damaged plants for years. I use it in spring around the root zone of perennials and occasionally put a pinch or two in my spray bottle for my plants in the home. I think the less is more addage works well here.

OrchidTalk --An Orchid Growers Discussion Forum brought to you by River Valley Orchidworks. A World Community where orchid beginners and experts talk about orchids and share tips on their care, cultivation, and propagation.